Merc and Ford side glass and B pillar, and top are different. Mercs were actually steel tops on converible bodies, that is why they looked dumpy. 39s had the windshield wipers on the top, 40s have the windshield wipers on the bottom of the windshield because the windshield did not open.
Actually this doesn't look like a Merc either.

Yes appearantly a Mercury body because of the way front windshield design, side chrome molding was set up, Slight different from a ford's standard coupe body itself.
Unfournately cant identify the exact year because the front end's all gone. But fournately that the body is an excellent candidate for restoration although and would be great use again! Drive down the memory lane turning back in GLORIFUL 4o's time :)
David